diagnostics: move diagnostics::edit_context -> diagnostics::changes::change_set

diagnostics: move diagnostics::edit_context -> diagnostics::changes::change_set

No functional change intended.

gcc/ChangeLog:
	* Makefile.in (OBJS-libcommon): Replace diagnostics/changes.o with
	diagnostics/edit-context.o.
	* diagnostic.cc: Update for move of diagnostics/edit-context.h to
	diagnostics/changes.h.
	(diagnostics::context::initialize): Update for renaming of
	m_edit_context_ptr to m_fixits_change_set.
	(diagnostics::context::finish): Likewise.
	(diagnostics::context::create_edit_context): Rename to...
	(diagnostics::context::initialize_fixits_change_set): ...this and
	update for other renamings.
	(diagnostics::context::report_diagnostic): Update for renaming of
	m_edit_context_ptr to m_fixits_change_set.
	* diagnostic.h (diagnostics::edit_context): Drop forward decl
	* diagnostics/edit-context.cc: Move to...
	* diagnostics/changes.cc: ...here.  Update for move of
	diagnostics/edit-context.h to diagnostics/changes.h.
	Rename diagnostics::edit_context to
	diagnostics::changes::change_set.  Rename diagnostics::edited_file
	to diagnostics::changes::changed_file.  Rename
	diagnostics::edited_line to diagnostics::changes::changed_line.
	* diagnostics/edit-context.h: Move to...
	* diagnostics/changes.h: ...here, renaming as above.
	* diagnostics/context.h (diagnostics::changes::change_set): New
	forward decl.
	(diagnostics::context::create_edit_context): Rename to...
	(diagnostics::context::initialize_fixits_change_set): ...this.
	(diagnostics::context::get_edit_context): Rename to...
	(diagnostics::context::get_fixits_change_set): ...this.
	(diagnostics::context::m_edit_context_ptr): Rename to...
	(diagnostics::context::m_fixits_change_set): ..this and update
	type.
	* diagnostics/diagnostics-selftests.cc: Update for renaming.
	* diagnostics/diagnostics-selftests.h: Likewise.
	* diagnostics/html-sink.cc: Update for above changes.
	* libgdiagnostics.cc: Likewise.
	* toplev.cc: Likewise.

gcc/c-family/ChangeLog:
	* c-common.cc: Update comment for renaming of edit_context.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/expensive_selftests_plugin.cc: Update for change
	from edit-context.h to changes.h.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>